Dental alloys must have a unique combination of properties. They should have high strength and tarnish resistance. They should have good castability, molding, working and burnishing characteristics so that they may be readily manufactured. They should also be compatible with other dental materials such as porcelain which they contact and have a suitable coefficient of expansion. The alloy must also have satisfactory color characteristics. It should not be discolored or cause discoloration of other dental materials with which it is in contact during the manufacturing process and later in service. The dental alloys must also meet the demanding requirements of non-toxicity.
Gold alloys have been the traditional dental alloys. Because of the high cost of such alloys and the ever more demanding technical specifications for such alloys, there has long been a need for improved and less expensive dental alloys. Many base metal alloys, such as nickel-chromium and cobalt-chromium have been proposed and found unsatisfactory. Palladium alloys have been proposed, some of which also contained silver or gold, see for example, U.S. Pat. Nos. 3,134,671; 3,819,366; 4,179,288; 4,261,744; and 4,319,877. Nos. 4,261,744 and 4,319,877 disclose palladium alloys which contain indium, tin and cobalt.
It is the object of the present invention to provide an improved dental alloy which has good working characteristics for manufacture, good service characteristics, and which is relatively inexpensive.